EP2253351B1 - Slit valve in combination with a pneumatic switching circuit of a ventilator device - Google Patents

Description

ARDS (acute respiratory deficiency syndrome) refers to a sudden lung injury caused by an acute inflammatory process of the lung tissue, in which the lung largely loses its ability to exchange gas. In ARDS, the permeability of the blood vessels in the alveoli increases, and the pressure in the vessels drops, while it increases in other parts of the lung tissue. This leads to a life-threatening breathlessness and to a deficiency of the blood with oxygen. The life-threatening oxygen depletion of the blood must be treated as soon as possible with the help of a mechanical respiratory support, ie artificial respiration with oxygen-enriched air. Non-invasive ventilation with a mere increase in the oxygen concentration of the supplied breath is often not sufficient for the treatment of ARDS, as ventilated ARDS patients have atelektante (ie collapsed) lung areas, which (recruited) and open only for a high ventilation pressure Gas exchange can be harnessed. For this, however, the patient must be intubated, ie the patient is a tube (tube) pushed through the mouth or through the nose into the trachea. Ventilation preferably takes place via an endotracheal tube or via a tracheotomy cannula. An endotracheal tube usually consists of a thin tube open at both ends, the lower end of which is pushed into the trachea. Just above the lower end is a block cuff, which can be inflated via a thin tube that runs along the side of the tube. This will then seal the trachea. At the upper end is the endotracheal tube with a standardized connector equipped to connect to a ventilator. A tracheotomy cannula is used in a tracheotomy. The tracheotomy cannula also features an inflatable "block" that allows ventilation while preventing pharyngeal secretions from reaching the lungs.

In artificial ventilation of ARDS patients, a residual pressure (PEEP - positive end-expiratory pressure) is preferably maintained at the end of the expiration. PEEP ventilation increases the pressure in the alveoli, which expands the air sacs, increasing the area for gas exchange and thus improving oxygen uptake. Furthermore, the risk of collapse of the alveoli during exhalation is reduced. In ARDS patients, the end-expiratory pressure for PEEP ventilation is often 10 mbar or more to prevent recollapse of the laboriously opened lung areas. In most cases, it is necessary to artificially ventilate an ARDS patient for several days or even weeks. During the course of ventilation, however, some steps are required in the clinical procedure, such as aspiration of fluids from the lungs, rearrangement of the patient, change of the tubing system, the filter or the ventilator. In performing these clinically necessary steps, the required lung pressure can not be sustained consistently, so that the damaged lung areas must be recruited again and again.

The US 4,351,328 describes an adapter designed to connect a ventilator and an endotracheal tube. The adapter is further provided with an opening which is closed by means of a valve. The valve is designed as a slit valve and can be pierced by the suction hose when it is inserted from the outside into the opening.

The US 4,416,273 discloses a connection adapter for an endotracheal tube. The adapter has one with a lamella valve provided port to introduce a suction catheter from the outside into the tube can.

The DE 32 04 110 C2 concerns a tracheal tube for artificial respiration. The lower part of the tracheal tube is surrounded by a balloon cuff, which can be inflated via a Aufblaskanüle so far that it rests against the tracheal wall. In the interior of the tracheal tube connected to a respirator breathing tube and a pressure measuring cannula are provided to measure the pressure drop in the breathing tube or the intratracheal pressure can.

The DE 198 38 370 C1 describes a device for removing sputum from a tracheal catheter. The device has three openings, a first opening being connected to the end of the catheter protruding from the trachea, a second opening being connectable to an air filter for cleaning and sterilizing the air to be inhaled, and a third opening having a drainage bag Sputum is connected. A spring-loaded piston for closing the third opening is controlled by the breathing air during inhalation and exhalation.

The DE 41 42 295 C2 relates to a valve for generating a control pressure in a pneumatic circuit. The valve has the configuration of a circular closure element and has notches, so that eight circular segments are formed, which are aufbiegbar to the peripheral line of the closure element. The amount of buckling varies depending on the pressure of the fluid acting on one side of the valve.

The DE 10 2005 014 650 B3 discloses a fitting having distal and proximal ends for connecting a tracheal tube and ventilator and a branch for insertion of a catheter. In the branch a valve made of an at least partially elastically deformable material is provided which forms a beak portion with a slot which is opened during insertion of the catheter.

Closed extractors, as shown in this document, only prevent the pressure drop during suction. A device change and the 48-hour change of the closed suction system, which is necessary for hygienic reasons, still lead to lung collapse and a subsequent burdening recruiting maneuver.

The EP 1 459 774 A1 discloses a slit valve for a medical fluid and a gas flow control in a cannula with a controller for opening and closing the slit valve. Here, the slit valve is designed with a closing membrane containing a centrally formed therein slot.

The GB 966,137 discloses providing in a slit valve an additional element which limits the slats generated by the slits in one direction in their propagation.

None of the above-mentioned documents deals with the ventilation of ARDS patients, and none of these documents disclose pneumatic circuit ventilators between a respirator and a patient that are designed to also provide a particular air pressure in the lungs of the patient to be ventilated then maintain, for example, when the ventilator is replaced.

It is therefore an object of the present invention to provide a valve for use in the pneumatic circuit of a ventilator, with the help of which the above-mentioned disadvantages are overcome. It is a particular object of the invention to provide a valve for use in or on a ventilator-coupled tube (eg an endotracheal tube or a tracheotomy cannula) with the aid of which a pressure drop in the lungs of a patient (in particular an ARDS patient) can be effectively prevented.

These and other objects are achieved by a slit valve having the features of patent claim 1. In the dependent claims advantageous and preferred developments of the slot valve according to the invention are given.

A significant advantage of the slit valve according to the invention is that the valve is bidirectional and responsive depending on the flow direction or effective direction of a fluid at different threshold pressures.

Another advantage is that the slit valve according to the invention is self-closing and only when a threshold pressure is exceeded in the open state passes to allow the passage of a fluid. The amount of fluid flowing through is dependent on the pressure of the fluid. The valve according to the invention can be flowed through from both directions (that is, bidirectionally), wherein the threshold pressure, which causes opening of the slit valve, is different depending on the flow direction. Preferably, the threshold pressure in a first direction is in a range between about 0 mbar and about 5 mbar and in a second direction in a range between about 5 mbar and about 15 mbar. The exact height of these threshold values, however, depends on the field of application of the valve and, for example, can also be in the range of well over 10 mbar up to a few 100 mbar.

The slit valve according to the invention is preferably used in the pneumatic circuit of a ventilator and is therefore provided in the flow path between the ventilator and the patient to be ventilated, especially an ARDS patient, which is preferably ventilated with PEEP. With the aid of the slit valve of the present invention, when disconnected from the endotracheal tube or tracheostomy tube (for example, when the ventilator is replaced), the pressure drop in the patient's lungs may be avoided below a predetermined pressure level of, for example, between about 5 and 15 mbar. The valve is further configured to allow for inhalation without requiring the patient to apply a large suction pressure. Therefore, the threshold value for opening the valve in the suction direction is preferably below 5 mbar. In the direction of exhalation, the required threshold pressure for opening the valve must be greater and is more than 5 mbar, preferably more than 10 mbar or in exceptional cases more than 15 mbar, these values also depending on the patient to be ventilated in a particularly advantageous embodiment, may vary depending on the severity of the ARDS and other factors. Furthermore, the valve is designed to allow the aspiration of fluids from the lung by means of a special cannula. The slit valve according to the invention has a Hygienic design that allows use for more than 1 week. In a preferred embodiment, the valve is designed in a special way so as not to hinder the respiratory flow during normal ventilation. For this purpose, the slit valve according to the invention is provided with manually operable means to easily make a changeover between different modes can.

In the preferred embodiment, the slit valve according to the invention is formed by a membrane made of elastic plastic or rubber. The membrane preferably has a round base shape, i. a circular outline. Conceivable, of course, other shapes, such as oval, rectangular or square, the round shape is preferred because of the symmetry. In the middle of the membrane a plurality of intersecting slots are provided, which extend completely through the membrane and thus form a plurality of circular segment-shaped lamellae. Thus, for example, a total of four slats are formed by two slots crossing at right angles, three slats are formed by three slits, etc. Designs with more than six slats are also possible.

In the idle state (ie substantially no pressure difference hiss the opposite sides of the membrane), the slats are closed, ie the slit surfaces of adjacent slats abut sealingly against each other. According to a first embodiment, the membrane lamellae lie in their closed position in a curved surface. This curved surface may for example have the shape of a dome or a spherical surface segment or the outer surface of a flat cone or a flat pyramid correspond. Regardless of the design chosen, the fins are designed to more easily open or flex in a first direction upon application of pressure (acting, for example, via a fluid to the diaphragm fins) than in a second direction. Consequently, no or only a small fluid pressure (first threshold pressure) is required in a first flow direction to move the fins from their closed position to their open position bend (ie, open the valve), while in the opposite second flow direction, a larger pressure (second threshold pressure) is required.

According to a second embodiment, the membrane lamellae lie in this closed state in a substantially planar plane and are designed to realize different threshold values for opening the valve or the lamellae when pressure is applied in different directions. This can be achieved in that the material thickness of the slats in an axial direction is thicker than the material thickness of the annular edge region or retaining ring of the valve membrane. As a result, it can be effected that the contact area of the slot surfaces in the axial direction is relatively large. At the same time, however, the located in the transition between the retaining ring and the slats pivot lines of the slats are slightly offset from the axial center of the radially extending contact areas between the slats in the axial direction, so that in an axial direction, a larger pressure must be built to the slats to pivot or fold from the closed position to the open position. Alternatively, the material thickness of the lamellae may increase in the radial direction towards the center of the valve membrane, starting from their pivoting lines, thereby causing a similar effect. It is also possible to provide an annular groove on one side of the valve diaphragm. Through this groove, the "film hinges" are formed for the membrane fins, but at the same time be displaced by the provision of the annular groove, the pivot lines of the joints in the axial direction. Consequently, even in this embodiment, the threshold pressure for opening the valve in one direction is greater than in the opposite direction. The height of the respective threshold values can be determined by the material thickness of the membrane, the depth of the groove and by the elasticity of the membrane material. Further, it is possible to provide the diaphragm fins on one side directly on the abutting slot surfaces between adjacent fins with axially extending projections so as to increase the contact surfaces of the slots in the axial direction, thereby simultaneously causing a relative axial displacement of the pivot lines of the fins becomes.

For example, the slit valve of the present invention is suitable for use in the respiratory circuit for positive pressure ventilation (e.g., PEEP) between a ventilator and the patient. But there are also other applications conceivable in which a similar valve function is desired.

The slit valve according to the invention preferably has a substantially tubular valve housing with two generally opposite ports and can be traversed in two opposite directions with breathing gas. As explained above, the slit valve according to the invention in the flow channel between the two terminals on a slit membrane which is fixed at its annular edge directly or indirectly in the housing and has in its center via incisions substantially radially separated membrane fins. The membrane fins are according to a preferred embodiment, at least partially curved so that when the valve is closed, the convex side of the curvature points in the direction of the patient. When exhaling a moderate pressure on the patient side against the convex curvature leads first to a compression of the curvature along the radial dividing lines (slots) between the membrane fins and thus to an obstruction of the flow channel. Only when a predetermined threshold pressure of, for example, about 10 mbar is exceeded, this blocking force is overcome, the lamellae are folded in the opposite direction (ie counter to the direction of the curvature), and the flow channel is released to be traversed by breathing gas. When the threshold pressure falls below again, the membrane lamellae fold back into their original curvature due to their own restoring forces, and the flow channel is blocked again. On inhalation, however, overpressure on the opposite side (ie on the side of the ventilator) against the concave underside of the arch leads to an immediate, nearly force-free flow of fluid towards the patient, since only a very small threshold is required to close the fins to open.

The valve according to the invention can also be designed as a "pop-up" valve. For this purpose, a depressible or foldable annular intermediate area is provided between the inner circular slot area and the outer retaining ring. In the closed state of the valve or in the state that prevails when the patient inhales and only a small threshold (pressure on the side of the ventilator) is required to open the membrane lamellae, this intermediate area is folded together or. When the patient exhales (over-pressure on the patient side), the folded intermediate area is unfolded first. As the pressure continues to rise and exceeds the stated threshold (e.g., 10 mbar or more), the membrane fins are also folded down. It has been found that the membrane lamellae are better pressed against each other when the intermediate area is folded and the pressure on the patient side is overpressure. Only when the intermediate region is unfolded does the transition section between the membrane lamellae and the intermediate region acquire the necessary flexibility to allow the membrane lamellae to be easily folded over when the patient-side pressure during exhalation exceeds the predetermined threshold value. Thus, the foldable intermediate region acts as a kind of security device against premature folding over of the membrane lamellae below the threshold pressure.

In a further advantageous embodiment of the invention, a release device is additionally provided, which folds out the membrane blades from the closed position upon actuation, so that the flow channel is released in the interior of the valve. In a preferred embodiment of the slit valve according to the invention, the valve is inserted between an endotracheal tube or a tracheotomy cannula on one side (patient side) and the filter, artificial nose, closed suction or Y-piece on the other side (ventilator side) Breathing circuit introduced. The valve has a housing, a slot diaphragm with, for example, four or six radially extending slots, thereby forming cut diaphragm fins, a rotary ring and an open holder. The open holder can be inserted into the effective range of the slit membrane, that the membrane slats of the slit membrane permanently release the flow center and represent no relevant flow resistance. The open holder has two oblique retaining lugs, which open through the housing in a running as an oblique path groove of the rotary ring. The rotary ring also has an annular groove into which a bead of the housing engages. As a result, the rotary ring is fixed against axial displacement on the housing. Upon rotation of the rotary ring of the open holder is moved axially over the two oblique tracks and can be optionally placed in a position near the Y-piece, where the open holder does not interfere with the membrane and a pressure drop in the patient's lungs below, for example, 10 mbar is avoided. In the opposite, near-patient position of the open holder engages with the membrane fins and pushes them out of the flow center, thereby allowing an unobstructed, bidirectional flow of fluid through the valve.

• Figur 1a zeigt eine schematische Draufsicht auf eine exemplarische Schlitzmembran gemäß der Erfindung.
• Figur 1b zeigt eine Querschnittsansicht durch Linie A-A aus Figur 1a, in der der gewölbte Lamellenbereich zu sehen ist. Die Pfeile stellen die Druckrichtung dar, bei der ein geringer Schwellwert zum Öffnen des Ventils erforderlich ist.
• Figur 1c zeigt eine Querschnittsansicht durch Linie A-A aus Figur 1a, in der eine alternative Ausgestaltung zu Figur 1b mit einer variierenden Materialstärke der Membranlamellen zu sehen ist.
• Figur 1d zeigt eine Querschnittsansicht durch Linie A-A aus Figur 1a, in der eine weitere alternative Ausgestaltung zu Figur 1c mit einer konstanten Materialstärke der Membranlamellen zu sehen ist, wobei die Materialstärke des Halterings deutlich geringer ist als die der Membranlamellen.
• Figur 1e zeigt eine Querschnittsansicht durch Linie A-A aus Figur 1a, in der noch eine alternative Ausgestaltung zu Figur 1d mit einer konstanten Materialstärke der gesamten Membran zu sehen ist, wobei zwischen dem Haltering und dem mittleren Lamellenbereich eine ringförmige Nut vorgesehen ist.
• Figur 2a zeigt eine Ausgestaltung der erfindungsgemäßen Schlitzmembran aus Figur 1b im geschlossenen Zustand.
• Figur 2b zeigt die Schlitzmembran aus Figur 2a in einem geöffneten Zustand, wobei der Druck in Richtung des Einatmens wirkt und nur ein sehr geringer Druck erforderlich ist, um die Membranlamellen nach unten zu drücken.
• Figur 2c zeigt die Schlitzmembran aus Figur 2a in einem geöffneten Zustand, wobei der Druck in Richtung des Ausatmens wirkt und ein recht hoher Druck-Schwellwert erforderlich ist, um die Membranlamellen nach oben umzuklappen.
• Figur 3a zeigt eine weitere bevorzugte Ausgestaltung des Schlitzventils aus Figuren 1 und 2 im geschlossenen Zustand.
• Figur 3b zeigt das Schlitzventil aus Figur 3a kurz vor Erreichen des geöffneten Zustands in Richtung des Ausatmens.
• Figur 3c zeigt eine Abwandlung des Schlitzventils aus Figur 3a im geschlossenen Zustand.
• Figur 3d zeigt das Schlitzventil aus Figur 3c kurz vor Erreichen des geöffneten Zustands in Richtung des Ausatmens.
• Figur 4 zeigt eine weitere Ausführungsform des erfindungsgemäßen Schlitzventils, das mit einer manuell zu betätigenden Freigabeeinrichtung versehen ist.

The present invention will now be described by way of example with reference to the drawings.

• FIG. 1a shows a schematic plan view of an exemplary slit membrane according to the invention.
• FIG. 1b shows a cross-sectional view through line AA FIG. 1a , in which the curved lamellar area can be seen. The arrows represent the direction of pressure, which requires a small threshold to open the valve.
• Figure 1c shows a cross-sectional view through line AA FIG. 1a in which an alternative embodiment to FIG. 1b can be seen with a varying thickness of the membrane lamellae.
• Figure 1d shows a cross-sectional view through line AA FIG. 1a in which another alternative embodiment too Figure 1c with a constant Material thickness of the membrane lamellae can be seen, the material thickness of the retaining ring is significantly lower than that of the membrane lamellae.
• Figure 1e shows a cross-sectional view through line AA FIG. 1a , in the still another alternative embodiment too Figure 1d can be seen with a constant material thickness of the entire membrane, wherein between the retaining ring and the central fin area an annular groove is provided.
• FIG. 2a shows an embodiment of the slit membrane according to the invention FIG. 1b in the closed state.
• FIG. 2b shows the slit membrane FIG. 2a in an open state, the pressure acting in the direction of inspiration and only a very low pressure is required to push the membrane lamellae down.
• Figure 2c shows the slit membrane FIG. 2a in an open state, the pressure acting in the direction of exhalation and a fairly high pressure threshold is required to fold the membrane lamellae upwards.
• FIG. 3a shows a further preferred embodiment of the slit valve FIGS. 1 and 2 in the closed state.
• FIG. 3b shows the slit valve FIG. 3a just before reaching the open state in the direction of exhaling.
• Figure 3c shows a modification of the slit valve FIG. 3a in the closed state.
• 3d figure shows the slit valve Figure 3c just before reaching the open state in the direction of exhaling.
• FIG. 4 shows a further embodiment of the slit valve according to the invention, which is provided with a manually operable release device.

The figures will be described in detail below. FIG. 1 Figure a shows a plan view of an exemplary slit membrane according to the invention in its simplest form. The slit membrane 1 has substantially the shape of a disc and is made of rubber, silicone rubber or a suitable elastic plastic material. The slit membrane 1 comprises a circular slat region 3 with slats 3a to 3d, which are formed by intersecting slits 4a, 4b, and an annular holding region 2, which surrounds the slat region 3 and serves to fasten the slit membrane in a preferably annular valve housing. In FIG. 1 a are two intersecting slots are shown, whereby four circular segment-shaped fins are formed. But it is also possible to provide three or more intersecting slots, which increases the total number of slats accordingly.

FIG. 1b shows a cross-sectional view through line AA FIG. 1a in which the curved lamellar region 3 can be seen along the slot 4a. In this embodiment, the membrane fins 3a-3d lie in their closed position in a curved surface, which in the present case has the shape of a dome or a spherical surface segment. However, the lamellae can also form the outer surface of a flat cone or a flat pyramid. In the illustrated rest state, the slats are closed, and the slit surfaces of adjacent slats abut sealingly against each other. The arrows 5 represent the direction of pressure of a fluid when there is an overpressure on the side of a ventilator (not shown), as is the case when the patient inhales. Here, only a small pressure threshold is required to fold down the vanes to open the valve. When exhaling (see also Figure 2c ) of the patient, a slight overpressure is first generated on the patient side, which presses against the downward convex curvature of the slats and to a mutual compression of the membrane lamellae and thus to a Locking the flow channel leads. Only when a predetermined threshold pressure between about 5 and 15 mbar is exceeded, this blocking force is overcome, the lamellae 3a-3d are folded upwards, and the flow channel is released. If the threshold pressure falls below again, the membrane lamellae fold back into their arched initial position due to their own restoring forces, and the flow channel is blocked again.

Figure 1c shows a cross-sectional view through line AA FIG. 1a in which an alternative embodiment of the slats 3a-3d can be seen. As shown, the lamellae have a thickness increasing towards the center, whereby in the region of the slots 4a, 4b, the contact surfaces between adjacent membrane lamellae increase in the axial direction. Since in the figures, the pivot lines 6 of the slats in the axial direction above the center 7 of the contact surface, the slats can pivot with slight pressure down, whereas a larger pressure is required to pivot the slats upwards.

Figure 1d shows an alternative embodiment Figure 1c in which the membrane lamellae 3a-3b have a constant material thickness which is greater than the material thickness of the annular holding region 2. Here too, the pivot line 6 of the lamellae lies in the axial direction above the center 7 of the contact surface between the lamellae. This allows the lamellae to be swiveled down with light pressure when inhaled, whereas a larger swelling pressure is required to pivot the louvers upwards.

Figure 1e shows a cross-sectional view through line AA FIG. 1a in which an alternative embodiment to Figure 1d can be seen with a constant thickness of the entire slit membrane 1. Between the retaining ring 2 and the middle slat region 3, an annular groove 8 is provided. The function of the different pressure threshold values in different flow directions is also realized in this embodiment.

It is obvious that the slit membrane 1 off FIGS. 1 a to 1 e in one preferably annular valve housing can be mounted, wherein the retaining ring 2 can be used for example in an annular groove in the interior of the valve housing. Other types of attachment are conceivable, such as gluing, welding, melting, etc.

FIG. 2a shows an embodiment of the slit membrane according to the invention FIG. 1b in the closed state. In this condition there is no pressure on both sides, or the pressures on both sides are below the threshold values.

FIG. 2b shows the slit membrane FIG. 2a in a downwardly open condition, wherein the pressure in the direction of inspiration is above a low predetermined threshold of, for example, 0 to 5 mbar required to push the membrane blades 3a-3d downward.

Figure 2c shows the slit membrane FIG. 2a in an open state, the pressure acting in the direction of exhalation. This pressure is above the threshold of, for example, 10 or 15 mbar, which is required to push the membrane blades 3a-3d upward.

FIG. 3a shows a preferred embodiment of the slit valve FIGS. 1 and 2 in the closed state or shortly before reaching the open state in the direction of inhalation (overpressure on the side of the ventilator). The valve 10 preferably has a substantially tubular valve housing 11 with two generally opposite ports and can be traversed in two opposite directions with breathing gas. The valve housing 11 may be configured to connect an adapter or a tube. Between the two terminals, a slot diaphragm 3 is provided, which is fastened to its annular holding area 2 on the valve housing. The slit membrane 3 may have any of the configurations as shown in FIG FIGS. 1 and 2 are shown. That in the FIGS. 3a to 3d shown valve 10 is designed as a "pop-up" valve. Between the inner circular lamellar region 3 and the outer retaining ring 2, a collapsible, annular intermediate portion 12 is provided, which may have various shapes, as in FIGS. 3b and 3d best seen. As in FIG. 3b 1, the intermediate region 12 is formed by a substantially tapered annular portion, whereas the intermediate region 12 in FIG 3d figure is formed as a cylindrical ring portion, which is followed by a radially outwardly curved wall portion, which in turn is connected to the retaining ring 2. FIG. 3a FIG. 12 shows the closed-state of rest of the valve or the condition prevailing when the patient is breathing in and only a low threshold of, for example, less than 5 mbar (overpressure on the side of the ventilator) is required to open the membrane fins 3. If the pressure threshold value is exceeded, the lamellae 3a-3d would open downward, as shown in FIG FIG. 2b is shown. It is obvious that the lamella area 3 is one of the in FIGS. 1 b to 1 e can have shown configurations.

The intermediate region 12 may, as in FIGS. 3a and 3c shown, folded together or into each other. In this state, the membrane fins 3a-3d are closed or are folded down when the pressure threshold value (pressure on the side of the ventilator = inhalation of the patient) is exceeded. When the patient stops inhaling, the slats are closed again due to their restoring force. When the patient starts to exhale, the lamellae are first pressed against each other, preventing the lamella from flipping over. Folding is further prevented by the folded intermediate portion 12 applying a radially inwardly directed force on the slats. As the pressure on the patient side continues to increase, the intermediate region 12 is deployed first, as in FIG FIGS. 3b and 3d is shown. In this state, the force acting on the lamellae through the intermediate region decreases, because only when the intermediate region is unfolded does the section between the membrane lamellae and the intermediate region acquire the necessary flexibility to allow the membrane lamellae to be flipped over in the direction of exhalation. Consequently the lamellae are then flipped up on the patient side when the pressure threshold (eg 10 or 15 mbar) is exceeded, as in Figure 2c is shown. When the patient stops exhaling again, the pressure on the patient side falls below the above threshold again, and the slats return to their closed starting position due to their restoring force. During the subsequent inhalation, the intermediate area is returned to the in FIGS. 3a and 3c folded position shown folded. Thus, the foldable intermediate portion 12 acts as a kind of protection against premature folding of the slats below a defined pressure threshold.

FIG. 4 shows a further embodiment of the slit valve according to the invention, which is additionally provided with a release device. The slit valve 20 has a sipe portion 3 in which a plurality of slit slats 3a-3d are formed. The slats have a similar configuration as in Figures 1b and 2a-2c , Only the extent of the curvature of the slats is in the embodiment of FIG. 4 greater. But the slats can also change the configuration Figures 1c-1e to have. Further, in the present embodiment, the retainer ring 2 is bent C-shaped downwardly / inwardly in the direction of the camber and configured to engage a correspondingly shaped recess 21 of a female tube connector 22. The female tube connector 22 is integrally connected to a male tube connector 24 to form the valve housing. The male tube connector 24 is configured to be connected to an opening of a Y-piece (not shown). In an advantageous embodiment, a closed suction device is mounted between Y-piece and slit valve, the suction cannula can penetrate the slit membrane axially for the suction of secretion. In addition to the housing formed by the female connector 22 and the male connector 24, the slit diaphragm 1 with, for example, four or six radially extending slots, the valve 20 also has a rotatably mounted on the housing 22, 24 rotary ring 25 and a slidably mounted in the housing 26 opener on. The open holder 26 can thus in the effective range of the slit membrane 1 or of the lamellar region 3 are inserted, that the membrane fins 3a-3d of the slit membrane are permanently opened in the patient direction, so as to release the flow center in the interior of the valve and to represent no relevant flow resistance.

The open holder 26 has two retaining lugs 27, which open through the housing (between the male and female tube connectors 22, 24) into the inclined track 28 of the rotary ring 25. The rotary ring 25 has, in addition to the oblique path 28 via an annular groove 29 into which a bead 30 of the housing engages. As a result, the rotary ring 25 is fixed axially on the housing. Upon rotation of the rotary ring of the open holder 26 is moved axially on the inclined track 28 and can thus be selectively placed in a position near the Y-piece (side of the ventilator), where the open holder does not interfere with the membrane lamellae and thus a pressure drop in the lungs the patient is avoided below, for example, 10 mbar. In the opposite, near-patient position of the open holder engages with the membrane fins and pushes them out of the flow center, whereby a bidirectional flow of fluid through the slit valve 20 is made possible.

Claims (15)

1. Slit valve in combination with a pneumatic switch circuit of a respiration apparatus, wherein the slit valve is formed in order to act bi-directionally and to respond depending on the flow direction of a fluid with different pressure thresholds, characterised in that the slit valve has a membrane (1), wherein several slits (4a, 4b) crossing each other are provided in the middle (3) of the membrane (1) which form several lamellae (3a - 3d), wherein the lamellae (3a - 3d) are formed such that with application of pressure they open easier in a first direction than in a second direction, wherein in the course of this the pressure threshold for opening the lamellae (3a - 3d) in a first direction is smaller than in the second direction.
2. Slit valve according to claim 1, characterised in that the slit valve is self-closing and only passes into the open state when crossing pressure thresholds which in dependency of the flow direction of a fluid differ in order to allow the fluid to pass.
3. Slit valve according to one of the preceding claims, characterised in that the expansion pressure in a first direction is in a range between 0. mbar and 5 mbar and in a second direction is in a range between 5 mbar and 15 mbar.
4. Slit valve according to one of the preceding claims, characterised in that the membrane (1) is limited by a retaining ring (2) at its outer edge and in that the membrane (1) is preferably made of elastic plastic or rubber.
5. Slit valve according to one of the preceding claims, characterised in that the membrane (1) has a round, oval, rectangular or square basic form.
6. Slit valve according to one of the preceding claims, characterised in that the slit areas of adjacent lamellae (3a - 3d) trigger sealingly against each other in the closed state.
7. Slit valve according to one of the preceding claims, characterised in that the thickness of the lamellae (3a - 3d) in the axial direction is thicker than the thickness of the annular edge region, wherein the thickness of the lamellae (3a - 3d) in the radial direction preferably increases from their pivot lines to the middle of the membrane (1).
8. Slit valve according to one of the preceding claims, characterised in that the lamellae region (3) bearing slits of the membrane (1) forms a curved surface, wherein the curved surface preferably has the form of a dome or a spherical segment respectively, or in that the curved surface corresponds to the outer surface of a flat taper or a flat pyramid.
9. Slit valve according to one of the preceding claims, characterised in that the lamellae (3a - 3d) are at least partly curved.
10. Slit valve according to claim 9, characterised in that the lamellae (3a - 3d) are curved such that the convex side of the curvature in the closed state points in the direction of a patient, wherein a moderate pressure on the convex side leads to an injection of the curvature along the slits of the lamellae (3a - 3d) and therefore to a blockage of the flow channel.
11. Slit valve according to one of the preceding claims, characterised in that the membrane (1) at its annular edge (2) is fixed directly or indirectly in a housing (11, 22, 24).
12. Slit valve according to one of the preceding claims, characterised in that a crushable or foldable annular intermediate space (12) is provided between an inner circular slit region (3) of the membrane (1) and the outer retaining ring (2).
13. Slit valve according to one of the preceding claims, characterised in that the slit valve has an additional release device (26), which when actuated folds out the lamellae (3a - 3d) out of a closed position, so that the flow channel inside the valve is released.
14. Slit valve according to claim 13, characterised in that the valve has a rotating ring (25) and an open keeper (26), wherein the open keeper (26) is inserted into the affected area of the membrane (1) such that the lamellae (3a - 3d) of the membrane (1) release the flow centre permanently and represent no relevant flow resistance, wherein the open keeper (26) has preferably two retaining (27), which result in an oblique path (28) of the rotating ring (25) through the housing (22, 24), wherein the open keeper (26) is moved axially in rotating the rotating ring (25).
15. Slit valve according to claim 14, characterised in that the rotating ring (25) has an annular groove (29), into which a bead (30) of the housing (22, 24) engages, whereby the rotating ring is fixed against axial displacement on the housing (22, 24).

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